[Beowulf] Keeping the Athlon MP cluster limping along

[Robert G. Brown]

On Wed, 8 Dec 2004, David Mathog wrote:

> It's official, the Tyan S2466 nodes get  "biggest PITA award"
> for systems that I've used. The two nodes that were crashing
> frequently had their power supplies  replaced and then they
> were stable for a couple of months.  Now they've both become
> unstable again.  

As you know, you have more than just my sympathies.  We have people who
are lined up with baseball bats in hand to give our dual 2466's a lick
if/when we can finally afford to move them out.  In fact, one person I
know is preparing a small but powerful explosive device to use on the
whole pile...;-)

> So rather than keep trying to fix these monsters I'm starting
> to think about the cheapest way to keep the cluster running by
> replacing just the mobo/CPU with something else (as I'm not
> expecting enough $$$ anytime soon to do more, and obtaining
> Athlon MPs and S2466N mobos now is problematical anyway.)
> I'll happily give up Tyan's serial line bios access for a system
> where I don't have to employ that feature quite so often!
> 
> The S2466N is an ATX form factor, each one has one Athlon MP
> 2200+ and 1 Gb of 2100 DDR RAM, a 40G ATA disk, a floppy
> and a little PCI graphics card in a 2U case.  If I could
> find a nice mobo/CPU combo for, oh, <$200 that could
> replace the S2466N and Athlon MP, and still do ECC, then I'd
> probably go that route to patch systems up as they break.
> Best if it has at least as much cache as the MP though.
> Is there anything out there fitting
> that description?  Historically ECC support isn't something
> that shows up on cheap mobos but maybe on some low end
> Athlon 64 variant?

I just bought an intermediate AMD64 mobo for my home cluster three days
ago.  The motherboard (ASUS) was $155, the CPU was $245 (for a slot 754
3400, which is really 2400 MHz, 128 MB L1, 512 MB L2 cache according to
their numbering scheme).  Also populated with a gigabyte of PC 3200
non-ECC memory it was about $500, and I'm very interested in seeing it
go head to head with my opterons.  I have NOT installed it yet so I
can't give you any speed reports.

Looking over the other prices from that vendor (intrex.com, although I
go to a local store) their cheapest AMD64 is the 2800 for $150, and
they had an MSI socket 754 motherboard for $100.  All these motherboards
seem to want non-ECC DDR400 (or slower) memory -- to get maximum
performance you'd likely want to replace the memory anyway.  So the
absolute minimum sounds like it would be around $250, with a gig of new
non-ECC memory around $350.

Full speed ECC memory adds a LOT to this.  Going socket 939 adds almost
nothing (and I'm wondering if I should have gone this way after Bill's
review of the AMD64 configs a few days ago).  Going socket 940 adds a
ton of money -- too much for a home box (and probably too much for your
upgrade).

Note that these are not pricewatch prices, so they are probably 20% or
so more than you could find on the street if you tried hard.

   rgb

-- 
Robert G. Brown	                       http://www.phy.duke.edu/~rgb/
Duke University Dept. of Physics, Box 90305
Durham, N.C. 27708-0305
Phone: 1-919-660-2567  Fax: 919-660-2525     email:rgb at phy.duke.edu